Targeting intracellular oncoproteins with dimeric IgA promotes expulsion from the cytoplasm and immune-mediated control of epithelial cancers

Dimeric IgA (dIgA) can move through cells via the IgA/IgM polymeric immunoglobulin receptor (PIGR), which is expressed mainly on mucosal epithelia. Here, we studied the ability of dIgA to target commonly mutated cytoplasmic oncodrivers. Mutation-specific dIgA, but not IgG, neutralized KRASG12D within ovarian carcinoma cells and expelled this oncodriver from tumor cells. dIgA binding changed endosomal trafficking of KRASG12D from accumulation in recycling endosomes to aggregation in the early/late endosomes through which dIgA transcytoses. dIgA targeting of KRASG12D abrogated tumor cell proliferation in cell culture assays. In vivo, KRASG12D-specific dIgA1 limited the growth of KRASG12D-mutated ovarian and lung carcinomas in a manner dependent on CD8+ T cells. dIgA specific for IDH1R132H reduced colon cancer growth, demonstrating effective targeting of a cytoplasmic oncodriver not associated with surface receptors. dIgA targeting of KRASG12D restricted tumor growth more effectively than small-molecule KRASG12D inhibitors, supporting the potential of this approach for the treatment of human cancers.

The Warburg effect: persistence of stem-cell metabolism in cancers as a failure of differentiation

Background

Two recent observations regarding the Warburg effect are that (i) the metabolism of stem cells is constitutive (aerobic) glycolysis while normal cellular differentiation involves a transition to oxidative phosphorylation and (ii) the degree of glucose uptake of a malignancy as imaged by 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is associated with histologic measures of tumor differentiation. Combining these observations, we hypothesized that the high levels of glucose uptake observed in poorly differentiated cancers may reflect persistence of the glycolytic metabolism of stem cells in malignant cells that fail to fully differentiate.

Patients and methods

Tumor glucose uptake was measured by FDG-PET in 552 patients with histologically diverse cancers. We used normal mixture modeling to explore FDG-PET standardized uptake value (SUV) distributions and tested for associations between glucose uptake and histological differentiation, risk of lymph node metastasis, and survival. Using RNA-seq data, we carried out pathway and transcription factor analyses to compare tumors with high and low levels of glucose uptake.

Results

We found that well-differentiated tumors had low FDG uptake, while moderately and poorly differentiated tumors had higher uptake. The distribution of SUV for each histology was bimodal, with a low peak around SUV 2-5 and a high peak at SUV 8-14. The cancers in the two modes were clinically distinct in terms of the risk of nodal metastases and death. Carbohydrate metabolism and the pentose-related pathway were elevated in the poorly differentiated/high SUV clusters. Embryonic stem cell-related signatures were activated in poorly differentiated/high SUV clusters.

Conclusions

Our findings support the hypothesis that the biological basis for the Warburg effect is a persistence of stem cell metabolism (i.e. aerobic glycolysis) in cancers as a failure to transition from glycolysis-utilizing undifferentiated cells to oxidative phosphorylation-utilizing differentiated cells. We found that cancers cluster along the differentiation pathway into two groups, utilizing either glycolysis or oxidative phosphorylation. Our results have implications for multiple areas of clinical oncology.

The Complexity of Omega-3 Fatty Acid Modulation of Signaling Pathways Related to Pancreatic Cancer

Cancer is a major public health problem worldwide and is the second leading cause of death in the United States. Although cancer death rate has dropped by 23% since 1991, there are certain types of cancer for which death rates are still increasing, such as pancreatic cancer. There is an urgent need to find new therapies that could help improve this dreadful outcome. In this regard, the role of nutrition in health and disease has attracted much attention. Several dietary components are involved in metabolic, physiologic and cell signaling affecting tumor growth and progression. Although lipids, and more specifically polyunsaturated fatty acids, have been traditionally studied due to their health effects in cardiovascular disease, it is now clear that they can impact an extensive array of cellular processes that influence a wide range of diseases such as type II diabetes, inflammatory disorders and cancer. These biological activities may be grouped as regulation of: (1) membrane structure and function, (2) intracellular signaling pathways, (3) transcription factor activity, (4) gene expression, and (5) production of bioactive lipid mediators. The aim of this review is to assimilate the current state of knowledge about these potential mechanism(s) of action and signaling pathways modulated by polyunsaturated fatty acids in pancreatic cancer.